How can Retin-A cause fat loss? I noticed a substantial amount from my cheeks, but I had no dietary of lifestyle changes (Photo)

Hi I took retina-a 0.05% in August 2013 for 3 months and after a few weeks of using it I noticed a substantial amount of fat had been lost from the fat pads on my cheeks. I had not dietary or lifestyle changes so is completely attributed to taking retin-a. I applied a very small amount, less than a pea seized amount every other night. So how can a cream do this to fat ? I've added a few before and after photos. The after photo was taken only a few week after the before, showing much more hollower cheeks.